The present invention refers in general to machine tools with swarf or chip removal.
Traditionally, in industrial plants that use such machine tools, the relative lubricant/refrigerant liquids and machining swarf are transported, generally via inclined floor-level channels, to filtration plants that separate the solid parts from the liquids so that the latter can be reutilised.
This solution involves evident complications due to the layout of the channels, as well as the space occupied by the channelling and flexibility problems in relation to the positioning of the machine tools.
Hence, it would be auspicious to eliminate these channels and connect the lubricant/refrigerant liquid discharges from the machine tools with the filtration plant via a network of overhead pipes, which is less complicated, less space-consuming and much more flexible when setting up. Nevertheless, this requirement does not reconcile with the presence of long metal swarf in the lubricant/refrigerant liquids. Such swarf is normally of variable length and even several centimeters long, and therefore cannot be transferred to the filtration plant connection piping using normal hydraulic pumps.
The object of this invention is that of solving this problem and to reduce the swarf length so as to enable the pumping of lubricant/refrigerant liquids containing swarf using normal hydraulic pumps.
According to the invention, this objective is achieved by a self-feeding shredder, characterized by the fact that it consists of a conveyor including a channel element for feeding the lubricant/refrigerant liquids in which a motorized screw conveyor sits, the end tip of which constitutes the advancement member of a shredding group, including an internally grooved cylindrical body arranged coaxially to the said end tip of the screw conveyor and a lobe rotor axially faced against the outside of the said grooved cylindrical body and controlled in rotation by the said screw conveyor.
The combined effect of the rotation of the screw and the presence of the grooves inside the cylindrical body of the shredding group creates an effective unwinding, straightening and stretching action on the elongated particles of metal swarf as they are self-fed to the rotor. The interaction between the lobes of the rotor and the extremity of the grooved cylindrical body faced against it produces a grinding and shredding action, reducing the size and length of the metal swarf particles to levels at which they can be pumped, together with the lubricant/refrigerant liquids, to the filtration plant.
The same advantageous functional result is achieved even in the case the shredding device according to the invention is employed for the mere disposal of the swarf produced by the machine tools, i.e. independently of the presence of a lubricant/refrigerant filtration plant, i.e. independently of the presence of a lubricant/refrigerant filtration plant, and/or of distribution and/or conveying systems for the lubricant/refrigerant liquids and swarf (e.g. even in the case the swarf are removed by means of collecting containers).
In order to render the unwinding and stretching effect on the elongated swarf more efficient, the aforesaid end tip of the screw conveyor has a diameter that is opportunely smaller than that of the rest of the aforesaid screw. This end tip is equipped with an opportune end tang that stands proud of the aforesaid cylindrical body and on which the lobe rotor is engaged for rotation.
Another characteristic advantage of this invention is that the motorised group driving the screw conveyor is equipped with a counter-rotation device, which is set up to automatically intervene during normal running in cases where rotation of the screw slows down or stops due to swarf clogging or blockages.